COR File

What are COR files and how to open them

Are you having problems opening a COR file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your COR files.

What is a COR file?

COR files have multiple uses, and 42's Core War Compiled Program is one of them. Read more about the other uses further down the page.

42's Core War Compiled Program

The 42's Core War Compiled Program format stores a "champion" binary for the Corewar game as implemented at 42 school. It is created by the assembler component ("asm" program) of the Corewar project when it converts a champion written in Redcode-style assembly (.s) into a binary form to be run by the virtual machine ("corewar" program). The format preserves both metadata (name, comment) and the compiled instructions so that the virtual machine can load, identify, and execute the champion in battle.

The format begins with a fixed-size header that includes the champion's "name" field followed by a "comment" or description field. These fields use zero-padded ASCII and fixed-length space allocations so that they occupy specific byte ranges. After the metadata, the compiled bytecode for the champion's instructions follows. The code is written so that each operation, operand encoding, and parameter span a precise number of bytes, as defined in the specification "Machine code / Encoding" portion of the 42 Corewar subject.

Files in this format begin with the four-byte sequence 0x00 EA 83 F3 in big-endian at offset 0.

How to open COR files

Important: Different programs may use files with the COR file extension for different purposes, so unless you are sure which format your COR file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested eight different COR openers which you will find listed below.

Last updated: September 2, 2026

All known file formats using extension .COR

While 42's Core War Compiled Program is a popular type of COR-file, we know of 2 different uses of the .COR file extension. Different software may use files with the same extension for different types of data.

WinArcadia Recording/macro

WinArcadia Recording/macro files store input log data captured by the WinArcadia (Windows) or AmiArcadia (Amiga) emulator for Signetics-2650-based machines. These files record a sequence of controller and keyboard inputs (macro events) triggered during gameplay, so that the exact same inputs can be replayed later. That allows use-cases like movie recording, tool-assisted speedruns, or simply automating gameplay segments.

The format is written by the emulator when a user activates its macro or recording feature. The file typically works in two modes: one where the emulator plays back the recording - that is, read and process the input events in order - and another where recording is ongoing after or during playback, for example to extend or overwrite part of a previous recording ("rerecording").

File size and contents are a logged stream of input events, likely timestamped or frame-based, along with emulator state necessary to interpret them. Exact encoding of events (which input, timings, etc.) is proprietary to WinArcadia/AmiArcadia and not publicly documented.

These files begin with a fixed byte signature: the first three bytes are BF 11 01 at offset zero.

Various apps that use files with this extension

These apps are known to open certain types of COR files. Remember, different programs may use COR files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about COR file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.